Touch weight

[Fred Sturm]

Vince,
	This seems, BTW, to be an argument for weighting a keyboard as a whole, 
using a template to position leads, as opposed to "individually weighting." 
Which is a notion that has a lot going for it. As Roger Jolly likes to say, 
individual weighting is usually just a way to cover up errors elsewhere. 
And, of course, using wipp assist springs allows one to reduce the overall 
moments of inertia. Exactly to what extent one should do this is an open 
question. And, I suppose, subject to a great deal of personal preference.
	I'm curious: have you calculated moments of inertia for a number of 
keyboards, and do you have some data to share?
Regards,
Fred Sturm
University of New Mexico

--On Friday, December 19, 2003 5:47 AM -0800 madelyn mrykalo 
<madvinmryk@yahoo.com> wrote:

>
> Ed-
> We measured the weight in grams of a lead for the mass (m).  I.e. 14.1
> grams for a 1/2 inch lead is usual, then for r we measured the distance
> of the lead from the middle of the balance hole to the middle of the lead
> in inches.  So I=14.1X4"  would be for one lead (I just picked a figure
> 4" for the distance).  Then if there is another lead, do the same for it,
> adding it to the first lead.  So I=14.1X4" + 14.1X2" (if the second lead
> is 2" from balance) and so  on.  This gets some figure that sort of
> arbitrarily represents the moment of inertia, larger in the bass, and
> graduating to smaller as we go up into the treble.  I think with some
> research the moment of inertia figure can come to mean something to us.
> Empirically finding out what kind of figures pianists like would help set
> a general standard, I think.
> It seems to me right now if you can get those figures to graduate
> smoothly you can really even out the feel.  Another question arises as to
> should we smooth out those figures between the sharps and naturals or let
> the sharps have a "lighter" number as they naturally do, because of their
> shorter length.
>
> Ed Sutton <ed440@mindspring.com> wrote:
>
>
> Vince-
>
> Never having learned calculus, I don't know how to work a formula like
> this.
> Assuming that I have
> -Strikeweight continuity within Stanwood's suggested range
> -Frontweight continuity within Stanwood's ceiling
> -Even and acceptable DW & UW
>
> How can I use this formula to improve action performance?
>
> Thanks!
>
> Ed Sutton
>
>
> ----- Original Message -----
> From: madelyn mrykalo
> To: College and University Technicians
> Sent: Friday, December 19, 2003 12:56 AM
> Subject: Re: Touch weight
>
>
>
> Hi-
>
> Of course you can have acceptable DW's & UW's and at the same time have a
> wide range of moments of inertia, some which may be acceptable and some
> which may not be.  Or the front weights could be too high.  That's why I
> don't think UW/DW alone tells us enough about how the action "feels".
>
>
>
> Here is a formula for moment of inertia (I):
>
>  I= m1r12 + m2r22 + m3r32 + ... + mnrn2
>
>
>
> Where m is the mass and r (radius) is the distance that the mass is from
> the balance hole of the key.  The key itself has some moment of inertia
> too.
>
>
>
> So the action in question (Wimís D) might weigh off acceptably (DW and
> UW), but also may have a too heavy a front weight, and/or moment of
> inertia.
>
>
>
> Stanwood has come up with a good standard of front weights.  Moment of
> inertia standards are a little more ambiguous at this point. More
> importantly is that the moments be reasonably smooth from key to key.
>
>
>
>
>
>
> Vince Mrykalo
> University of Utah
>
>
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